I-beams are shaped like the letter “I” to maximize the moment of inertia, which in turn maximizes its resistance to bending and deflection when used as a beam or floor joist. It is well known that I-beams are the most efficient structural members when subjected to bending, and they are widely used in both light-framed and heavy-duty constructions.
In light-framed construction, support for structures is conventionally provided by members composed of a single material, predominantly either wood or metal. These single-material members are often vulnerable to failure due to characteristics of the material. For example, while wood is weak in tension and very vulnerable to fire and termites; a metal stud has inherent problems of pre-mature failure due to weak connection and local buckling. Conventional steel I-beams can be very heavy. Furthermore, use of certain materials can have a negative effect on the environment. For example, inefficient use of timber wastes trees, a valuable natural resource. Also, timber is often treated for use in exterior construction which can add pollutants to the environment. In another example, pressure treated wood produces a large volume of waste water with pollutants.
In heavy duty construction, composite techniques are often used to achieve higher structural performance. A composite structure combines different materials together to form a new structure. Since it fully utilizes the potential of individual materials, the advantages of composite structures have been well recognized in the engineering community during the past decades.
However, past applications, such as concrete-filled steel tubes and composite floor decks, mostly involve combining steel and concrete in various forms, and are primarily used in commercial buildings and infrastructures.
What is needed is to introduce composite techniques in light-framed construction to allow for lighter and stronger I-beam members.